A Cooperative Network Coding Strategy for the Interference Relay Channel.

In this paper, we study an interference relay network with a satellite as relay. We propose a cooperative strategy based on physical layer network coding and superposition modulation decoding for uni-directional communications among users. The performance of our solution in terms of throughput is evaluated through capacity analysis and simulations that include practical constraints such as the lack of synchronization in time and frequency.We obtain a significant throughput gain compared to the classical time sharing case

Generic Approach for Hierarchical Modulation Performance Analysis: Application to DVB-SH

Broadcasting systems have to deal with channel diversity in order to offer the best rate to the users. Hierarchical modulation is a practical solution to provide several rates in function of the channel quality. Unfortunately the performance evaluation of such modulations requires time consuming simulations. We propose in this paper a novel approach based on the channel capacity to avoid these simulations. The method allows to study the performance in terms of spectrum efficiency of hierarchical and also classical modulations combined with error correcting codes. Our method will be applied to the DVB-SH standard which considers hierarchical modulation as an optional feature.Comment: To appear in WTS 2011 proceeding

Combining Adaptive Coding and Modulation With Hierarchical Modulation in Satcom Systems

We investigate the design of a broadcast system in order to maximize throughput. This task is usually challenging due to channel variability. Forty years ago, Cover introduced and compared two schemes: time sharing and superposition coding. Even if the second scheme was proved to be optimal for some channels, modern satellite communications systems such as DVB-SH and DVB-S2 rely mainly on a time sharing strategy to optimize the throughput. They consider hierarchical modulation, a practical implementation of superposition coding, but only for unequal error protection or backward compatibility purposes. In this article, we propose to combine time sharing and hierarchical modulation together and show how this scheme can improve the performance in terms of available rate. We introduce a hierarchical 16-APSK to boost the performance of the DVB-S2 standard. We also evaluate various strategies to group the receivers in pairs when using hierarchical modulation. Finally, we show in a realistic case, based on DVB-S2, that the combined scheme can provide throughput gains greater than 10% compared to the best time sharing strategy

Trade-off between spectrum efficiency and link unavailability for hierarchical modulation in DVB-S2 systems

Broadcasting systems have to deal with channel variability in order to offer the best spectrum efficiency to the receivers. However, the transmission parameters that optimize the spectrum efficiency generally leads to a large link unavailability. In this paper, we study the performance of hierarchical and nonhierarchical modulations in terms of spectrum efficiency and link unavailability for DVB-S2 systems. Our first contribution is the design of the hierarchical 16-APSK for the DVB-S2 standard. Then we introduce the link unavailability to compare the performance of hierarchical and non-hierarchical modulations in terms of spectrum efficiency and link unavailability. The results show that hierarchical modulation is a good alternative to nonhierarchical modulation for the DVB-S2 standard

Florence de Caigny, Sénèque le Tragique en France (XVIe-XVIIe siècle)

La fin de la Renaissance, l’âge baroque et l’âge classique sont des époques de l’imitation. Pour la tragédie, le modèle sénéquien est essentiel, et l’ouvrage de Florence de Caigny, Sénèque le Tragique en France (XVIe-XVIIe siècles), nous offre enfin la synthèse attendue. Que les œuvres du dramaturge romain aient été traduites intégralement à trois reprises au XVIIe siècle et donné lieu à trente-trois imitations différentes pendant la période étudiée suffit à suggérer l’ampleur de leur récepti..

Making hierarchical modulation more flexible

In a broadcast system using the hierarchical modulation, the system delivers several streams with different waveforms and required Signal-to-Noise Ratio (SNR), typically SD- TV and HD-TV. At the application layer, each stream is delivered with a particular rate. The physical layer must be defined in order to optimize the protection of each stream with respect to the double constraints of both the data rates and the SNR thresholds. We show in this paper that a standard like DVB-SH is not always well adapted to meet these system constraints in operational typical cases. After exposing the current limitations of a classical hierarchical modulation approach, we present two possible adaptations to address these operational requirements and offer more flexibility in hierarchical modulation design

Practices and dynamics of immobility: The institutionalized control of induction in consultancy

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Temps de la connaissance, temps de l'action: vers une réconciliation

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Processus de contrôle et organisation par projets : une étude de cas

Control Processes and project based management: a clinical surveyThis paper is based on a specific clinical survey. The framework for analysis it introduces aims at presenting an articulation of instrumental and organizational control processes in a project based structure. The co-occurrence of standard and project management specific processes is deeply analyzed. Thereafter, the text casts light onto their interactions, which are the main factor that may facilitate or hinder the previously considered processes.Procesos de control y organización por proyectos: un estudio de casoEste artículo se basa sobre un estudio de caso único. Su marco conceptual articula procesos instrumentales e organizacionales de control en una estructura administrada por proyectos. Se analiza precisamente la coincidencia de procesos estándares y otros conceptualizados específicamente para la gestión por proyectos. Después se examinan las interacciones de estos procesos como los factores que pueden facilitarlos u obstaculizarlos.Fondé sur l’étude de cas d’un laboratoire pharmaceutique, cet article propose un cadre d’analyse dont l’objet, dans un premier temps, est de présenter une articulation des processus de contrôle instrumentaux et organisationnels mis en œuvre dans une structure par projets. La coexistence des processus standards et de ceux conçus spécifiquement pour une gestion par projet fait l’objet d’une étude approfondie. Dans un second temps, le texte met en évidence leurs interactions possibles, lesquelles sont susceptibles de faciliter ou de mettre en difficulté les différents processus examinés préalablement

Temps et Contrôle de Gestion

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